Scand J Work En viron Health 2000;26(3):257-262
Radiographic knee osteoarthritis in floorlayers and carpenters by Lilli Kirkeskov Jensen, MD, Sigurd Mikkelsen, DM, lnger P Loft, MSG, Winnie Eenberg, BSc, lnge Bergmann, MD,3 Vibeke Lggager, MD3 Kirkeskov Jensen L, Mikkelsen S, Loft IP, Eenberg W, Bergmann I, Lsgager V. Radiographic knee osteoarthritis in floorlayers and carpenters. Scand J Work Environ Health 2000:26(3):257-262.
Objectives The aim of the present study was to examine the relationship between knee-straining work and radiological findings of knee osteoarthritis and to study the relation between radiological findings and self-reported knee complaints and clinical signs of knee osteoiuthitis. Methods The material consisted of 133 floorlayers, 506 carpenters, and 327 compositors, 26-72 years of age, who had completed a questionnaire and reported no previous knee trauma. A stratified sample of these questionnaire respondents, 50 floorlayers, 51 carpenters, and 49 compositors, were radiologically examined for knee osteoarthritis by 2 radiologists. The X-ray films were independently assessed by 2 radiologists and blinded with respect to knee complaints, trade, and age. R ~ s u ~The ~ sradiological investigation showed estimated prevalences of knee-osteoarthritis (grades 2 4 ) for 14% of the floorlayers, 8% of the carpenters, and 6% of the compositors (not significantly different). For the subjects 250 years of age the estimated prevalences of the combination of radiological grades 2 4 for knee osteoarthritis and knee complaints during the last 12 months were 29% [95% confidence interval (95% CI) 1744%], 9% (95% CI 1-26%), and 1% (95% CI 1-10%) for the floorlayers, carpenters, and compositors, respectively. Radiological grades 2 4 were mainly found for subjects above the age of 50 years, subjects with knee complaints, and floorlayers. Radiological knee osteoiuthritis was positively associated with self-reportedknee complaints and with clinical signs of intraarticularand retropatellar crepitation. C O ~ C ~ U S ~The O ~data S suggest that work in which a considerable amount of time is spent in knee-straining positions may be a risk factor for the development of knee osteoarthritis above the age of 50 years. Key terms clinical examination, compositors, knee osteoarthrosis, knee-straining work, questionnaire,radiological investigation, self-reported knee complaints. Previous studies have shown an increased frequency of radiological knee osteoarthritis among miners (1, 2), pipefitters, and welders (3), possibly related to kneeling o r squatting. However, the amount of knee-straining work in these trades was poorly described. A study of floorlayers, including a quantitative description of kneestraining work, was negative, but this study included only subjects below 50 years of age (4). The purpose of the present study was to examine the relation between knee-straining work and knee complaints, physical findings indicating knee disorders, and radiological knee osteoa~thsitis.Knee-straining work was defined as work in kneeling, knee-supporting (weightbearing on the knees), or squatting work positions. The study was a cross-sectional study of male floorlayers, carpenters, and compositors between 26 and 72 years of 1 2 3
age. The results concerning the amount of knee-straining work in the 3 trades, knee complaints, and physical findings have been published separately (5). Video recordings of representative work tasks showed that the floorlayers had knee-straining work in 56% of their workhours, and the corresponding figure for carpenters was approximately 25%. Compositors had no knee-straining work (5).
Subjects and methods The study material consisted of 133 floorlayers, 506 carpenters, and 327 compositors who had completed a questionnaire on aspects of their work, knee complaints,
Clinic of Occupational Medicine, Glostrup Hospital, Glostmp, Denmark. Department of Occupational and Environmental Medicine, Skive Hospital, Skive, Denmark. Department of Radiology, Glostrup Hospital, Glostrup, Denmark.
Reprint requests to: Dr Lilli Kirkeskov Jensen, Department of Occupational and Environmental Medicine, Skive Sygehus, Resenvej 25, DK-7800 Skive, Denmark. [E-mail:
[email protected]] Scand J Work Environ Health 2000, vol26, no 3
257
Radiographic knee osteoarthritis
previous knee trauma, medical conditions, height, weight, smoking, and participation in sports. The subjects with a previous knee trauma (eg, meniscal lesions and ligamental ruptures) and those with diseases such as rheumatoid arthritis and gout were excluded. The clinical study included 295 subjects, selected at random with variable sample fractions from 9 strata defined by the 3 trades and the following 3 categories of knee complaints: never, previously but not within the last 12 months, within the last 12 months. A sample of subjects participating in the clinical study was further invited to participate in the radiological examination. These subjects were invited at random from the 9 strata, aiming at a total of 50 subjects for each trade and in such a way that approximately 213 within each trade were selected from subjects who had had knee complaints within the last 12 months. Clinical findings were not considered in the selection of the subjects. The study material is presented in table 1.
X-rays of the anteroposterior and lateral positions of the knees were taken while the subject was lying down. The X-rays were assessed independently by 2 medical specialists in radiology (IB, VL) and were made without knowledge of the subject's trade, age, or reported knee complaints. In case of disagreement on the grade, a final joint assessment was made. The assessments were carried out according to the criteria defined by Icellgren & Lawrence (6), which categorize knee osteoarthritis by severity as follows: grade 0 = no changes, grade 1 = doubtful narrowing of joint space and possible osteophytic lipping, grade 2 = definite osteophytes and possible narrowing of joint space, grade 3 = moderate multiple osteophytes, definite nassowing of joint space and some sclerosis and possible deformity of bone ends, grade 4 = large osteophytes, marked narrowing of joint space, severe sclerosis, and definite deformity of bone ends.
1
Table 1. Results of the radiological examinations by sampled
strata (trade and knee complaints during the last 12 months), age, and selected combined strata. (95% CI = 95% confidence interval) Complaints Questionnaire Sample during the last respondents for X-ray 12 months (N) total (N)
Knee osteoarthritis grades 2-4 N
%
/
Reproducibility of the radiological assessment The agreement between the assessments of knee osteoarthritis by the 2 radiologists is shown in table 2. The kappa-coefficient was 0.52 [95% condifence interval (95% CI) 0.43-0.611 if all grades were considered and 0.61 (95% CI 0.44-0.78) if the grades were dichotomized as grades 0-1 and 2 4 .
95%CI
Analysis Floorlayers 4 0 years 250 years All Carpenters 4 0 vears 250 years All Compositors 4 0 years 250 years All Yes Floorlayers 4 0 years 250 years All Carpenters
